How to import .pdf file into Blender
Luckily PDF is a standardized format that will wrap both vector and raster elements.

Depending on the PDF in question, it should be viable to open it using any vector based application (Illustrator / Inkscape) or design publishing document application (InDesign or Scribus) and peel apart the various entities you require, or even save en masse to a vector or raster format as required.

If the document entities are raster elements, it would likely be most ideal to export them to a standardized raster file format such as TIFF. Be careful to match the native resolution of the raster elements to avoid inadvertent rescaling / resampling.

If the document entities are vector splines, both InDesign and Inkscape should be capable of pulling apart the actual splines for saving as SVG. Beware however in that you may see odd quantization of point positions or fill colour strangeness. Anything beyond basic fill colours and position or shapes will likely not translate to the import. Make sure to have enough subdivisions when importing the SVG file as the bezier knots may not be rendered correctly otherwise.

As a last resort and the worst possible case that you require a spline based version of a rasterized element, both Illustrator and Inkscape offer a method to do a quantized colour based outlining automatically via their tools. It may require some experimentation to get a reasonable set of splines, but it is possible.
The bulk of this is exactly as Duarte pointed out in his comment, with further detailed instructions to help the solution along.